Perforating gun for well casings



Aug. 5, i952 J, o, ow 2,605,834

PERFORATING- GUN FOR WELL CASINGS Filed Jan. 6, 1948 Patented Aug. 5, 1952 UNITED. STATES PATENT OFF-ICE aeoass if j I c I PERFORATING GUN ronvvrrlnonsmcs James 0. Tow, Huntington.ParlntCalif assignorto McCullough Tool Company; Vernon, Califl, a corporation of Nevada Application January 6, 1948, Serial No. 715

.3 Claims.

My invention relates to guns of the kind used for perforating well casings by shooting projectiles therethrough.

The objects of my invention are, first, to provide a perforating gun that is of simple construction and economical to make; second, to make .efiicient use of the propellant and to so achieve great perforating ability with a relatively small quantity of propellant material; third, to make close spacing of shots practical in a hard shooting gun; and fourth, to provide for safe and easy loading of the gun.

The invention is illustrated in the accompanying drawing in which, Fig. 1 is a vertical sectional view of a preferred form of my invention; and. Fig. 2 is a horizontal section taken on the line 2-2 of Fig. 1.

With reference to Figures 1 and 2 the construction is as follows:

A cylindrical body I has one or more bores I l, which are defined by cylindrical walls l5, and end walls I 3. The axis of each bore ll preferably intersects the axis of the body I!) at 90.

The body H) has a fire hole l2, the axis of which preferably coincides with the axis of the body and so (preferably) intersects the axis of each of the bores I I.

At its upper end the fire hole [2 terminates in a chamber 2| defined by the wall [4. The body [0 is provided at its upper end with a-threaded box 20 adapted to receive a sub of more or less standard design and not here shown as it is not a part of this invention. This sub may be one of types in general use-one which is 'aflixed to a wire rope which rope is used for lowering the gun into the well and Withdrawing it therefrom. This sub is adapted to receive a primer used in firing the gun, and which primer is fired electri pushed into place against the projectile as shown.

In my invention it is essential that the projectile when in firing position covers the junction of the fire hole with the bore ll. This placement of the projectile to cover the junction of the fire hole with the bore is an important part of my 2 invention. This position of the projectile substantially seals ofi the propellant from any void cavity until the projectile'has moved forward to uncover'the junction of the fire hole with the bore.

Since in practice the diameter of the projectile is made slightly less than the diameter of the bore (so that there is a loose fit) there is a flash-back of fire or hot gas between the projectile and the bore wall to the propellant, sufiicient to ignite the propellant, when the primer is ignited and fire or hot gas therefrom is forced down the fire hole against the first projectile.

As the first projectile is fired and uncovers the juncture of the fire hole with the bore, fire or hot gas is forced down the fire hole to the second projectile and the firing process continues and so on until all of the projectiles have been fired. When the pressure of gas from ignition of the primer or propellant comes to bear on the upper side of a projectile, it forces the projectile against the lower wall of the bore, thus increasing the clearance between the upper side of the projectile and the upper wall of the bore. This pressure against the upper side of the projectile tends to lock the projectile to some extent against movement until ignition of the propellant has begun.

When the sub used with this gun (and which screws into box 20) is provided with a sufliciently powerful primer, the primer I9 may be eliminated. If desired, several guns embodying this invention may be joined together end to end by providing a suitable threaded pin on the lower end of the gun body, and by continuing the fire hole through to the bottom of the gun. When used singly the fire hole can be plugged with a screw at the bottom of the gun and a bull nose guide screwed on to the pin.

Having thus described my invention I claim:

1. In a perforating gun of the character described, the combination of a body having a plurality of bores extending transversely into said body and a longitudinally extending fire hole of restricted cross section communicating with said bores, projectiles in said bores in positions to cover junctions of said fire hole with said bores, propellant charges filling said bores behind said projectiles, said projectiles being so formed with relation to the walls of said bores as to provide a passageway for passage of hot gases from said fire hole to said propellant charges, and a primer charge in communication with said fire hole in such position that hot gases proceed sequentially from one to another of said bores in the order of their arrangement along the fire hole;

2. A perforating gun as defined in claim 1, having seals in front of said projectiles.

3. In a perforating gun, the combination of a body, a plurality of laterally extending bores in said body, said bores being closed at their inner ends, a longitudinally extending fire hole of restricted cross-section intersecting each of said bores between the ends of the bores; agperforating projectile in each of said bores in position to cover the fire hole, a propellant charge filling each of said bores between the inner end of the projectile and the closed inner end ofthelbore, and a.v primer charge in communication withsaid fire' hole adjacent one end thereof, said-projectiles permitting fiame from said firehole to pass-be 4 tween the projectiles and the walls of their respective bores to their respective propellant charges.

JAMES O. TOW.

REFERENCES CITED The following references are ot record in the file of this. patent:

TENTS 2351,179- Aloi M June l3, 134A 

